set of jaws wedged into a hollow sleeve and held inplace by a threaded capSTEAM PISTON ASSEMBLYThe launching engine piston assembly (see fig.4-25) consists of left and right hand launching pistonsand attaching parts. The launching engine pistons areinstalled side by side in the launching engine cylindersthe shuttle assembly provides the connection for onelaunching piston to the other along with the connectionto the aircraft. The pressurized steam in the launchingengine cylinders drives the launching engine steampiston assemblies. They, in turn, drive the shuttle.Component parts of each piston assembly are the steampiston, the barrel, the connector, the strip guide, thepiston guide, and the tapered spearThe barrel serves as the chassis for the othercomponents of the assembly. The piston is bolted to theaft end of the barrel; the piston rings installed on thepiston seal the space between the piston and thecylinder wall. The cylinder cover segmented sealassembly acts as an extension of the piston into andthrough the cylinder slot. This seal assembly consists ofa housing, three upper seal segments, and six lower sealsegments. The upper seal segments press against thecylinder covers, and the lower seal segments pressagainst the sides of the cylinder slot to prevent the lossof steam pressure from behind the steam pistons as thepiston assemblies move through the cylinders duringthe power stroke. The connector and the strip guide arebolted to the top of the barrel. The connector lifts thesealing strip off its seat to permit passage of the shuttleassembly along the cylinder. The strip guide returns thesealing strip to its seat after the connector passes underit, minimizing loss of steam pressure as the pistonassembly advances through the power stroke. Inaddition, the connector has interlocking "dogs," whichcouple with matching "dogs" on the shuttle assembly toeffect the connection between the connectors and theshuttle assembly.The tapered spear and bronze piston guide arebolted to the forward end of the barrel. The piston guideacts as a bearing surface for the piston assembly andkeeps it centered with respect to the cylinder walls. Thetaperedspearworksinconjunctionwiththewater-brake cylinder assemblies to stop the pistonassemblies and shuttle at the end of the power stroke.SHUTTLE ASSEMBLYThe shuttle assembly (see fig. 4-26) carries theforward motion of the pistons to the aircraft by meansof a launch bar attached to the aircraft nose gear andconnected to the nose gear launch shuttle spreader. Themeshing of interlocking dogs of the piston assemblyconnectors and the shuttle frame connect the shuttleand the piston assemblies.The shuttle is essentially a frame mounted onrollers. Two pairs of rollers fitted with roller bearings4-18NUTBOLTCOTTER PINRUBBINGSTRIPCONNECTORDEFLECTORRINGSPEARSUPPORTGUIDEBOLTPISTONGUIDESTUDBARRELPISTONCYLINDERCOVER SEALSEALING-STRIPGUIDEABEf0426PISTONRINGSFigure 4-25.Launching engine steam piston assembly.